1. Field of the Invention
The present invention relates generally to memory devices having stacked die configurations with configurable inputs and outputs (I/O). Specific embodiments relate to stacked die configurations without requiring redistribution layers (RDLs) to allow through wafer interconnects (TWIs) or edge bonding. Indeed, embodiments of the present invention relate to die that incorporate path selectors, which enable configuration of each die for a particular stacking requirement.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Processing speeds, system flexibility, and size constraints are typically considered by design engineers tasked with developing computer systems and system components. Computer systems typically include a plurality of memory devices which may be used to store programs and data and which may be accessible to other system components such as processors or peripheral devices. Typically, memory devices are grouped together to form memory modules such as dual-inline memory modules (DIMMs). Computer systems may incorporate numerous modules to increase the storage capacity of the system.
Die stacking has recently emerged as a powerful tool for satisfying requirements for increased memory storage capacity within restricted packaging space. Die stacking includes the process of mounting multiple chips on top of one another within a single semiconductor package. Packages having a number of vertically stacked chips or die in a single package (i.e., die stacking) advantageously increase the amount of memory that can be located within a given footprint on the substrate or printed circuit board on which the die stack is arranged. Further, die stacking may enable shorter routing interconnects from chip to chip, thus increasing signal speeds between chips, reducing noise, and reducing cross-talk. Another benefit of die stacking is that surface-mount to printed circuit board assembly is simplified because fewer components are required to be placed on the printed circuit board.
As processing demands and storage capacity continue to increase, while system size continues to decrease, die stacking is becoming increasingly useful for different memory configurations. For example, requirements for dynamic random access memory (DRAM) configurations can make it desirable or even necessary to stack die to increase density or to increase I/O widths. Current stacking techniques generally require inclusion of a redistribution layer (RDL) on each DRAM to allow through wafer interconnect (TWI) or edge bonding. It should be noted that inclusion of such an RDL adds costs. Additionally, inclusion of an RDL generally requires uniquely configured die to be used within a die stack for certain stack elements. Indeed, to accommodate stacking requirements for each particular die, each layer of a die stack will typically have a different RDL configuration.
Embodiments of the present invention may address one or more of the problems set forth above.